I am stunned that there has been no formal explanation on how Sakaar exists after being consumed by Galactus so publicly.

I appreciate something happened in some book so that Galactus is now a Life-giver but was that ever explained in this key series? … and how does that work? All the people on Sakaar were just magically reverted to their status quo before the destruction of their planet?

Cho has no questions about this?

Very confusing.
Not happy such an enormous explanation isn't forthcoming.

Like Cth mentioned, we're in a new Marvel Universe now. The old one (universe 7) ended (earths colliding, Beyonders,..) in the beginning of the last Secret Wars and the new one was created at the end of the series. Universe 8.
So, a brand new universe! Everything that happened the last 70 years
doesn't really have to matter anymore.